Cham Lab UPDATED ACTUAL Exam
Questions and CORRECT Answers
pH meter - CORRECT ANSWER - thin walled bulb of glass containing 0.1M HCL in
contact with a metal wire electrode.
in solution, potential is et up across thin glass wall
compares signal to signal in standard buffer solution
buffer effectiveness depends on - CORRECT ANSWER - pH, concentration, volume and
identity
buffer capability at different pH ranges - CORRECT ANSWER - phosphate buffer
what colour is ONP - CORRECT ANSWER - yellow
at 420 nm
Jablonski Diagram - CORRECT ANSWER - An energy diagram that illustrates the
electronic states of a molecule and the transitions between them;
the states are arranged vertically by increasing energy and grouped horizontally by spin
multiplicity.
within any energy level (S) there are - CORRECT ANSWER - additional different energy
levels arising from different vibrational states (V1,V2)
how long does absorption take
how long is molecules excited for - CORRECT ANSWER - 10^ -15 seconds
, 10^-12 seconds, excited e- returns to one of the vibrational rotational levels associated with the
ground state
=coupled with loss of heat
light source used depends on - CORRECT ANSWER - wavelength instrument can operate
at
consistency of light source intensity
wavelength output
durability
cost
monochromator - CORRECT ANSWER - separate the light emitted from the lamp into as
many different distinct wavelengths as possible
= uses prisims or gratings
= grating more common: highly uniform and accurate etching patterns
= can have wavelength selection at less than 0.1 nm
our lab spectrophotometers focus the light - CORRECT ANSWER - with mirrors and
lenses
focus light into 1mm diameter, 8mm above the cuvette bottom
micro-volume spectrophotometer - CORRECT ANSWER - compress 1-2.5uL between 2
pedestals
compressed sample forms a short column and light is delivered and det3ected using fiber optical
cable inserted into the center of both pedestals
detectors - CORRECT ANSWER - quantify intensity and sometimes wavelength of light
convert light to electrical signal and amplify it
to send to computer
Questions and CORRECT Answers
pH meter - CORRECT ANSWER - thin walled bulb of glass containing 0.1M HCL in
contact with a metal wire electrode.
in solution, potential is et up across thin glass wall
compares signal to signal in standard buffer solution
buffer effectiveness depends on - CORRECT ANSWER - pH, concentration, volume and
identity
buffer capability at different pH ranges - CORRECT ANSWER - phosphate buffer
what colour is ONP - CORRECT ANSWER - yellow
at 420 nm
Jablonski Diagram - CORRECT ANSWER - An energy diagram that illustrates the
electronic states of a molecule and the transitions between them;
the states are arranged vertically by increasing energy and grouped horizontally by spin
multiplicity.
within any energy level (S) there are - CORRECT ANSWER - additional different energy
levels arising from different vibrational states (V1,V2)
how long does absorption take
how long is molecules excited for - CORRECT ANSWER - 10^ -15 seconds
, 10^-12 seconds, excited e- returns to one of the vibrational rotational levels associated with the
ground state
=coupled with loss of heat
light source used depends on - CORRECT ANSWER - wavelength instrument can operate
at
consistency of light source intensity
wavelength output
durability
cost
monochromator - CORRECT ANSWER - separate the light emitted from the lamp into as
many different distinct wavelengths as possible
= uses prisims or gratings
= grating more common: highly uniform and accurate etching patterns
= can have wavelength selection at less than 0.1 nm
our lab spectrophotometers focus the light - CORRECT ANSWER - with mirrors and
lenses
focus light into 1mm diameter, 8mm above the cuvette bottom
micro-volume spectrophotometer - CORRECT ANSWER - compress 1-2.5uL between 2
pedestals
compressed sample forms a short column and light is delivered and det3ected using fiber optical
cable inserted into the center of both pedestals
detectors - CORRECT ANSWER - quantify intensity and sometimes wavelength of light
convert light to electrical signal and amplify it
to send to computer
